1,172 research outputs found
Enhancing the ecological and functional roles of shade trees in cocoa farms:participatory tree diversification in Ghana
Machine learning methods to forecast temporal pattern of Aedes mosquito species using meteorological variables in Ontario, Canada
Dietary iron overload. the generation of reactive oxygen species and hepatocarcinogenesis in experimental rats (Part 1)
A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand In fulfilment of the requirements for the degree of Doctor of Philosophy
Johannesburg, 2003Dietary iron (Fe) overload, originally referred to as Bantu Visceral Siderosis, is an Reloading condition that is still prevalent in rural populations of sub-Saharan Africa. The better known Fe loading disease, hereditary haemochromatosis (HFI) is frequently complicated by hepatocellular carcinoma (HCC) and, in rare instances this occurs in the absence of cirrhosis. The latter, together with recent evidence that dietary Fe overload in the Black African carries an increased risk for HCC, suggests that excessive hepatic iron may itself be carcinogenic. The aim of the study was to determine if Fe alone could induce HCC in experimental rat models and, if so, to investigate possible mechanisms of hepatocarcinogenesis. 360 Wistar albino rats (Rattus norvegicus) were divided into 6 groups. The first group, the control animals, was designated C group. Groups 2-6 were Fe-fed alone or in combination with other chemicals: group 2 Fe alone (Fe group), group 3 (Fe + V) vitamins A & E supplementation [50 mg all trans-retinol (vitamin A) and 500 mg a-tocopherol (vitamin E) per kg diet], group 4 (Fe - V) received a diet totally devoid of vitamins A & E, group 5 (Fe + ASA) received 20 mg aspirin (ASA) per day, group 6 (Fe + Cu) received 300 mg/kg diet of copper sulphate (CuS04) supplementation for 12 months followed by 3% copper hydroxide carbonate [CuC03»Cu(0H)2]IT201
Influences of shading and fertilization on on-farm yields of cocoa in Ghana
Article Purchased; Published online: 31 August 2016Most cocoa farms in Ghana are cultivated in complex agroforest systems, with plant growth and cocoa productivity being affected. The objective of this study was to investigate how shade trees affect cocoa yield, temperature and soil nutrients in low-input cocoa systems. Establishing plots on 24 farms in four locations (districts) in Ghana, we assessed the influence of varying canopy cover and fertilization on cocoa yields. Results showed no relationship between canopy cover and cocoa yields in the light crop season (February to August). For the main crop season (September to January), there was an interaction between shade and yields: Yields were higher on no-shade plots than on shaded plots in two districts, whilst there were no differences at the two other districts possibly due to differences in precipitation and soil nutrient status. On the other hand, there was a positive effect of increased canopy cover on yields within the shaded plots. Soil nutrient analyses revealed no significant differences between shaded and no-shade plots and adequate levels of N, K+, Fe2+, Cu2+ and Zn2+ were recorded. However, soil contents of P, C, Mg2+ and Ca2+ were below recommended values. Peak temperatures recorded in the cocoa canopies were above the recommended range for this species. Although shade trees had a slight modifying effect on peak temperatures, the magnitude appeared too small to have any practical effects
Children\u27s Mental Health
The study of children’s mental health has largely been the domain of developmental psychologists and psychiatrists. These studies focus on parental mental health, and examine its direct and indirect effects, through a family’s psychosocial environment. Relatively little attention is given to socio-structural factors. By contrast, the sociology of mental health focuses on such structural factors as poverty and income, examining the extent to which stressors and strains may pattern the effects of these factors on children’s psychopathology. Adding to the divergence in research is the use of maternal reports in the assessment of children’s mental health. These reports often reflect mothers’ own mental health status and are inherently biased. Using data collected from 560 couples in London, Ontario, the current study moves beyond the scope of these disciplines to assess the effects of parental socio-structural and stress characteristics in relation to parental psychopathology. It addresses the issue of bias by using both maternal and paternal reports of their children’s mental health. In a final set of analyses, the results that are obtained using both parents’ reports are reconciled through an assessment of possible factors that may predispose either parent to overreport their children’s psychopathology. Findings indicate a moderate association between social structural characteristics and children’s mental health. This association is mediated by parental stress, which by itself is a direct and independent predictor of children’s mental health. The effect of parental distress, however, appeared to be a function of the parental report that was utilized. When mothers’ reports were used, their distress correlated with children’s psychopathology. Similarly, fathers’ distress mattered only when their own reports were used. Parental distress, independently and in relation to social structural, stress and family relationships, also contributes very little to the discrepancies in mothers’ and fathers’ reports of their children’s mental health. The findings of this study support the need for children’s mental health studies and intervention that transcends a focus on parental psychopathology to include an improvement in the social conditions of children
Treatment duration of topics in senior secondary school core mathematics in Ghana: a case study of Cape Coast district
The purpose of the study was to investigate whether the intended time of 160 minutes per week for 96 weeks was adequate for the treatment of the SSS Core Mathematics. The study used simple random sampling method to select two mixed, two single-sex female and two single-sex male Senior Secondary Schools in the Cape Coast Education District of the Central Region of Ghana. The study involved 790 students. Three achievement tests in mathematics were used to collect data. The data were analyzed by means of student t-test. The results showed that the intended time of 160 minutes per week for 96 weeks for the SSS Core Mathematics Program was inadequate. African Journal of Educational Studies in Mathematics and Sciences Vol. 2(1) 2004: 59-7
Distribution of tree seed and seedlings:the ICRAF/Danida Programme on Improved Seed Systems for Agroforestry in African Countries (ISSAAC)
Determination of Soil Erosion and Sediment Yield in the Bonsa River Basin Using GIS and Revised Universal Soil Loss Equation (RUSLE)
The Bonsa river is an important tributary of the Ankobra river in the Western Region of Ghana. The catchment of the Bonsa river has been undergoing rapid land cover changes due to human activities such as farming, illegal mining, population growth, among others which are likely to promote soil erosion and sediment yield in the river basin. To estimate the amount of soil eroded over a period and subsequent sediment yielded along the Bonsa river basin, the Revised Universal Soil Loss Equation (RUSLE) was integrated with Geographic Information System (GIS) to model the spatial distribution patterns in soil erosion and sediment yield within the catchment. Data used included annual rainfall records, soil map, Digital Elevation Model (DEM) and land-use map of the study area. Parameters of the model were determined and converted into raster layers using the raster calculator tool in ArcMap to produce a soil erosion map. The concept of Sediment Delivery Ratio (SDR) was applied to determine the annual sediment yield by combining a raster SDR layer with soil erosion map. The predicted soil loss and sediment yield values were found to be low. This may be due to high soil protective cover provided by vegetation as well as low topographic relief in the river basin. Though, the elements and processes responsible for soil erosion and sediment yield prevailing in the basin was found to be low, adverse situations could be developed with time if the prevailing conditions are not checked, as soil erosion is a natural gradual slow process. The gains made could be sustained by putting measures in place to control human activities, particularly, illegal mining (galamsey) in the basin, indiscriminate cutting down of trees and farmining activities along the Bansa river basin. This study will support monitoring, planning of water resources and help to improve sustainable water quality
Geospatial Assessment of Vegetation Changes around the Odublasi Quarry in Ghana
This study examined drivers of vegetation cover changes around the Odublasi quarry, analyzed trends of the change, and areas around the quarry prone to these drivers. Stakeholders were interviewed to identify drivers of vegetation cover change, while satellite imagery of the area from 2007, 2012, 2013, and 2014 were used for trend analysis. Field mapping of trees in the area was undertaken to acquire baseline data of vegetation for use in future studies and restoration projects. Identified drivers were; the construction of a new access road; switch in livelihoods of the local community members from small-scale quarrying to extracting biological resources around the quarry site; unsustainable farming and wood logging practices around the quarry; social exclusion; and afforestation programme around the quarry. A rising and falling trend in vegetation cover was observed in satellite images of the quarry site from 2007 to 2014. Activities around the quarry like shifting cultivation farming was a key driver of this undulating trend. Habitats along the access road to the quarry were identified to be vulnerable to the drivers of vegetation cover change and needed critical attention in any environmental restoration efforts
Challenges associated with ground water resources development in northern Ghana
It is estimated that groundwater contributes about 62 percent of the total water requirement of Ghana. It contributes an average of 67 percent to Northern Ghana’s domestic water needs. The groundwater resources of Northern Ghana are obtained from a variety of hard rock units, comprising basement complex (crystalline) systems and varying Neoproterozoic sedimentary rock types and, therefore, have varying hydrogeological characteristics. Some of the hard crystalline and Neoproterozoic rocks are overlain by a thick argillaceous overburden of high porosity and low permeability characteristics. Groundwater development in these hard rocks is structurally-controlled and successful boreholes are characterised by variable yields, which range from less than 0.2 m3 h-1 to 500 m3 h-1 at depths ranging from 40 - 160 m. The hard rock aquifers of Northern Ghana are generally discrete, giving rise to localised flows, thus, making regional aquifer evaluations rather challenging. Even though groundwater constitutes the main water supply sources, its development is fraught with challenges that range from exploration through drilling to water quality issues. These challenges have been noted to be highly related to the nature and characteristics of the underlying geological formations. This paper discusses some of the challenges that have been experienced during the long period of hydrogeological field practices in the northern part of the country
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